In the left tusk of the elephant shot by Sir Victor Brooke (p. 115), the pulp-cavity was wholly obliterated, its place occupied by an exceedingly dense nodular dentine. This tusk was diseased. In the right tusk of the same animal the pulp-hollow extended from the base through half the imbedded portion, or thirteen and a half inches. In a pair of tusks owned by Col. Douglas Hamilton, of the British army, the pulp-cavity occupies ten inches and a half of the imbedded length. From this it is evident that the length of a tusk cannot be accurately determined from mere observation, as in a large elephant the sockets are from one foot six inches to one foot nine inches in length; so that an animal might have a tusk three feet and a half long, and show only one foot and a half of it, the gum alone concealing about four inches. As the ivory is so soft at the base of the tusk, it is evident that it can be easily broken; and, if a bullet or spear strikes this spot, it becomes embedded, and eventually incorporated, in the tusk. Workers in ivory are often surprised to find a leaden bullet in the solid ivory. In a collection in London, there is a section of a tusk which was cut at a piano-forte manufactory in 1805, which has a wrought-iron musket-ball firmly embedded in it; and other instances can be seen in the museum of the London University. [Illustration: PLATE I. FIG. 1.—Molar Tooth of African Elephant. ” 2.—Molar Tooth of Asiatic Elephant. ” 3.—Molar Tooth of Elephas Americanus. ” 4.—Skull of Dinotherium. ” 5.—Molar Tooth of Mastodon giganteus. FIG. 6.—Head of an Elephant, showing the muscles. _B._ Section of the trunk. FIGS. 7, 8, 9.—Show the Uses of the Trunk. FIG. 10.—Section of the Skull of an Indian Elephant. _s._ air sinuses. _n._ nostrils. _b._ brain. _m._ molar tooth. _t._ tusk.]